Antigens for vaccination and/or diagnostic purposes are typically single antigens from a pathogen, or complex mixtures of multiple and unknown antigens of a pathogen such as inactivated bacteria or viruses. Depending on the particular type of pathogen, single antigens may provide a quantifiable signal in diagnostic test. However, due to variations among individuals in their immune response profiles, single antigen tests are often not sufficient to obtain useful diagnostic information with useful specificity and sensitivity. In addition, where the single antigen is used as a vaccine, variability of individual immune response and potential prior exposure often limit usefulness of single antigens. Finally, while some complex mixtures of multiple and unknown antigens are useful for vaccine development, they typically carry the risk of adverse reactions, or even reactivation of the pathogen.
More recently, multivalent vaccine preparations have become available where in a single dose, multiple and distinct antigens, from multiple and distinct serotypes, of a single pathogenic organisms were combined (Prevnar™: Heptavalent vaccine against Streptococcus pneumoniae capsular serotypes 4, 6B, 9V, 14, 18C, 19F, and 23F). While such mixed preparations tend to provide a broader range of protection against different serotypes, various difficulties nevertheless remain. Most significantly, where a single antigen fails to elicit an immune response, coverage to the corresponding serotype is not present. Thus, combination of single defined antigens from several serotypes merely combines benefits and problems associated with the single antigens. Moreover, none of the heretofore known antigens is generally applicable to differentiate among stages, secondary infections, etc., as the signal is either impossible to deconvolute (e.g., compound signal from inactivated pathogen) or only provides a single data point.
Therefore, while numerous methods of identification and use of antigens are known in the art, all or almost all of them suffer from one or more disadvantages. Consequently, there remains a large, unmet need to provide improved compositions and methods of antigens for diagnostic and therapy.